1. Field of the Invention
The present invention relates to data transmission systems, and more particularly to a missile telemetry system.
2. Description of the Prior Art
It is a well-known fact that RF radiation from missile or space vehicle telemetry systems is severely attenuated during re-entry into the earth's atmosphere to the point that information is lost by reason of the missile passing through this "blackout" region. A tape recorder has been used in previous systems to record the telemetry data and to transmit the data directly from playback after a suitable delay. The tape recorder required a controlled "on" time, retaping for repeated output, and has a potential for jamming of the tape.
Also, standard IRIG telemetry proportional-bandwidth FM subcarriers only handle up to 5,000 Hz nominal, or 8,000 Hz maximum with constant bandwidth FM subcarriers, so that it is not possible to retrieve data over 8,000 Hz in frequency response by using existing FM subcarrier channels.